The present invention relates to process state detector for detecting physical states of a process, and more particularly to a process state detector which is capable of grasping the long term change of sensors for measuring physical states of a process and estimating the lifetimes of the sensors.
In the prior art process state detector for detecting physical states of a process, in order to detect accurately the process state, a main sensor (e.g., a differential pressure sensor) for measuring a specific physical state of a process and compensating sensors (e.g., a static pressure sensor and a temperature sensor) for measuring other physical states are provided on a substrate of a semiconductor sensor. In this connection, prior to the detection of the actual plant data, the relationship between the output characteristics of the main sensor and those of the compensating sensors is previously obtained. Then, when measuring the actual process data, the outputs of the compensating sensors compensate for the output of the main sensor to detect accurately the physical states of the process.